Estimating diffusion through flake-filled membranes

Falla, Wayne R.; Mulski, Michael J.; Cussler, E. L.

doi:10.1016/0376-7388(96)00106-8

Cited by 162 publications

(123 citation statements)

References 10 publications

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“…Such flakes reduce permeability of any polymer by increasing tortuosity and reducing the area available for diffusion. Our past studies and others (Michaels et al, 1975;Wakeman and Mason, 1979;Cussler et al, 1988;Falla et al, 1996) show that these reductions depend only on the volume fraction and the shape of the flakes; they do not depend on the size of the flake or the properties of the polymer. In this sense, the results echo those of Clerk Maxwell (1881) for spheres and of Rayleigh (1892) for cylinders.…”

Section: Introductionsupporting

confidence: 50%

Reactive barrier films

2001

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Section: Introductionsupporting

confidence: 50%

Reactive barrier films

2001

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“…For instance, the crystallization of PETBB55 from the melt reduces the oxygen permeability by a factor of 5. The effect is described well by a model that considers only a random dispersion of impermeable platelets in a permeable matrix, 66 and this corroborates the poor spherulitic development, loosely organized lamellae, and pronounced secondary crystallization of PETBB55. 67 Modeling the more modest effect of cold crystallization by heating the quenched PETBB55 glass above T g leads to a consideration of small isotropic crystals embedded in a permeable matrix.…”

Section: Highlightmentioning

confidence: 52%

Oxygen transport as a solid‐state structure probe for polymeric materials: A review

Hiltner

Liu

et al. 2005

J Polym Sci B Polym Phys

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ABSTRACT:In the quest to elucidate the solid-state structures of polymers, insight into the amorphous phase is particularly elusive. Although the permeability of small molecules is often measured as an important performance property, numerous researchers have found that a deeper analysis of the transport characteristics provides insight into polymer morphology, especially if used in combination with more usual characterization techniques. The transport of small gas molecules senses the permeable amorphous structure and probes the nature of the free volume. In recent years, our interest in the gas barrier of polyesters has resulted in an unusual opportunity to investigate the nature of the free volume in the polymer glassy state. This effort has been aided by access to aromatic polyesters with designed variations in their chemical structure. This review focuses on oxygen transport, supplemented with other methods of physical analysis, as a probe of the excess-hole free volume. The review addresses the profound effects of orientation and crystallization on the free volume of the glassy state. The discussion also presents a simple odel for the gas permeability of the isotropic glass based on lattice concepts and tests more sophisticated models for the gas permeability of semicrystalline polymers. The final section addresses other opportunities for fruitful applications of oxygen transport as a solid-state structure probe.

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“…13,16 Several were 2-D studies of the cross-sections of the stratum corneum (or membrane), estimating the macroscopic diffusivity in the trans-membrane direction from geometric arguments, 23 Monte-Carlo calculations 16 or by measuring the pathlength directly from micrographs. 41 For the 3-D structure, the method of asymptotic expansions was used to find the effective diffusivity for both impermeable and permeable corneocytes.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Modeling Framework of Transdermal Drug Delivery

2009

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Abstract-This study addresses the modeling of transdermal diffusion of drugs to better understand the permeation of molecules through the skin, especially the stratum corneum, which forms the main permeation barrier to percutaneous permeation. In order to ensure reproducibility and predictability of drug permeation through the skin and into the body, a quantitative understanding of the permeation barrier properties of the stratum corneum (SC) is crucial. We propose a multiscale framework of modeling the multicomponent transdermal diffusion of molecules. The problem is divided into subproblems of increasing length scale: microscopic, mesoscopic, and macroscopic. First, the microscopic diffusion coefficient in the lipid bilayers of the SC is found through molecular dynamics (MD) simulations. Then, a homogenization procedure is performed over a model unit cell of the heterogeneous SC, resulting in effective diffusion parameters. These effective parameters are the macroscopic diffusion coefficients for the homogeneous medium that is ''equivalent'' to the heterogeneous SC, and thus can be used in finite element simulations of the macroscopic diffusion process. The resulting drug flux through the skin shows very reasonable agreement to experimental data.

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Estimating diffusion through flake-filled membranes

Cited by 162 publications

References 10 publications

Reactive barrier films

Reactive barrier films

Oxygen transport as a solid‐state structure probe for polymeric materials: A review

Multiscale Modeling Framework of Transdermal Drug Delivery

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